CN108677096A - A kind of strategic oil reserve tank steel plate and its manufacturing method based on Oxide Metallurgy - Google Patents

Abstract

A kind of strategic oil reserve tank steel plate and its manufacturing method based on Oxide Metallurgy, steel plate yield strength >=490MPa, 610~730MPa of tensile strength, yield tensile ratio≤0.90；Manufacturing method is：Heating and thermal insulation after continuous casting billet, then roughing and finish rolling is made, is cooled down with the speed direct quenching of >=50 DEG C/s, it is air-cooled after heating tempering.The steel plate of the present invention is simultaneously suitable for 10 ten thousand steres, 15 ten thousand steres and the manufacture of the above capacity large size strategic oil reserve tank；When steel plate carries out high heat-input welding under the conditions of heat input is more than 200KJ/cm, 20 DEG C of postwelding welding heat affected zone ballistic work is not less than 80J；It is expected to change into the welding of single side single pass V-type to the two-sided two pass time X-type welding manner that 25~60mm steel plates are limited during current petroleum storage tank is constructed, it can reduce nearly 1 half when Welder, it significantly improves petroleum storage tank speed of application and strategic oil reserve library construction cost is greatly lowered, there is good popularizing application prospect.

Description

A kind of strategic petroleum reserve tank steel plate and its manufacturing method based on oxide metallurgy

technical field

The invention belongs to the technical field of metallurgy, and in particular relates to a strategic oil reserve tank steel plate based on oxide metallurgy and a manufacturing method thereof.

Background technique

Strategic oil reserves are crucial to ensuring national energy security. The first phase of my country's oil reserve construction has been completed in the four coastal cities of Zhenhai, Zhoushan, Dalian, and Huangdao at the end of 2008, initially forming a net import volume of about 30 days. The size of crude oil reserves.

Usually, a 100,000 m ³ oil storage tank requires a total of 1948.5 tons of steel, and the cost of the tank body plus the value of crude oil is as high as hundreds of millions of yuan. If an accident occurs, the economic loss and environmental pollution will be serious; therefore, the oil The comprehensive performance requirement of the storage tank steel plate is high strength, high toughness and easy welding; especially to ensure the welding efficiency of on-site construction, the longitudinal welds of large storage tanks are required to be welded with a large heat input greater than 100KJ/cm. How to ensure that the high heat input after welding The embrittlement tendency of the welded heat-affected zone due to grain coarsening is small, and the low-temperature impact toughness is not lower than the technical requirements of the base metal, which is the key technology for the research and development of steel plates for oil storage tanks.

From the second phase of the construction project of 100,000 cubic meters of oil storage tanks in China, domestic steel plates have been used successively. The invention patents such as application number 200810119502.0, application number 200810224734.2 and application number 201410791633.9 are the domestic oil storage tank steel plate production that was formed at that time and has been used until now. Mainstream technology, its main feature is that it adopts off-line quenching + tempering or TMCP + tempering process to produce steel plates with a thickness of 12-33mm, a yield strength of 490MPa, and a tensile strength of 610-730MPa. In terms of grain coarsening, the traditional fine TiN particle pinning austenite growth mechanism is adopted. With this mechanism, under the condition of reasonable and stable production process, although the steel plate can withstand a large heat input of 100kJ/cm Welding requirements, however, since TiN will start to dissolve when the temperature reaches 1350°C, when the temperature of the welding heat-affected zone reaches or exceeds 1400°C, the volume fraction of TiN dissolved will even reach 88%, resulting in the loss of most of the TiN particles Inhibiting the growth of austenite grains, if considering the process or chemical composition fluctuation factors that may occur during the actual operation of the steel plate production plant, it is difficult to ensure that each steel plate actually used in the oil storage tank construction base can meet the thermal requirements. The input reaches the HAZ quality and performance requirements under the welding condition of 100kJ/cm; therefore, the current status quo is that the oil storage tank construction unit has to strictly limit the heat input to weld under the condition of far below 100kJ/cm, resulting in a thickness greater than 25mm The longitudinal seam of the steel plate can only be made with X-shaped grooves, and the front and back sides are welded once respectively, but the single-sided single-pass welding of V-shaped grooves cannot be realized, which virtually increases the welding construction cost of the oil reserve depot by nearly 1. In addition, the maximum thickness of steel plates used for oil storage tanks of 100,000 cubic meters is only 33mm, while the maximum thickness of steel plates used for oil storage tanks of 150,000 cubic meters and above will reach 60mm. The input welding performance must also be enhanced by nearly double. Therefore, in order to improve the quality and performance level of domestic oil storage tank steel plates and meet the construction needs of large oil storage tanks of 150,000 cubic meters and above, it is urgent to solve the insurmountable problems of existing technologies. Research Development of thick steel plates for domestic oil storage tanks capable of withstanding welding heat input greater than 200kJ/cm and its production method.

Contents of the invention

The purpose of the present invention is to provide a strategic petroleum reserve tank steel plate based on oxide metallurgy and its manufacturing method. The method is based on C-Mn steel, based on the basic principle of oxide metallurgy (Oxides Metallurgy), through reasonable chemical composition design , select appropriate alloy additives and addition methods, use metallurgical process reactions to refine and spheroidize inclusions in steel, and form high-melting point composite inclusions with controllable chemical structure. At the same time, it can also induce the formation of dense acicular ferrite with large-angle grain orientation, which can effectively improve the toughness of the welded heat-affected zone.

The composition of the strategic petroleum reserve tank steel plate based on oxide metallurgy of the present invention contains C 0.03-0.10%, Si 0.10-0.30%, Mn 1.2-2.0%, P≤0.015%, S≤0.008%, Ti 0.005～ 0.03%, Ni 0.01-1.0%, B 0.0001-0.002%, Cr 0.05-0.5%, Mo 0.05-0.3%, Nb 0.01-0.03%, Cu 0.01-1.0%, Al 0.001-0.03%, N 0.002-0.007% , O 0.001～0.006%, also contains one or more of Mg, Ca, Zr and RE, and the rest is Fe and unavoidable impurities; when Mg, Ca, Zr or RE are contained, the contents are: Mg 0.0001～0.005%, Ca 0.0001～0.008%, Zr 0.0001～0.02%, RE0.0001～0.02%; its carbon equivalent C _eq ≤0.40%, where C _eq ＝C+Mn/6+(Cr+Mo+V) /5+(Ni+Cu)/15.

The steel plate of the strategic oil storage tank based on oxide metallurgy has a thickness of 10-60mm, a yield strength of ≥490MPa, a tensile strength of 610-730MPa, an elongation of ≥17%, an impact energy of -20°C of ≥80J, and a yield ratio of ≤0.90.

The steel plate of the above-mentioned strategic petroleum reserve tank based on oxide metallurgy contains a large number of fine titanium-containing composite inclusions, the particle size range of titanium-containing composite inclusions is 0.01-0.55 μm, and the area density is ≥ 2.9×106 pieces/mm ² ; titanium-containing composite inclusions The number of inclusions is more than 4 times that of traditional steel. At the same time, these inclusions have a good affinity with MnS, so that MnS inclusions are very easy to gather in the outer layer and distribute spherically. , in addition to improving the low-temperature impact toughness of the heat-affected zone of high heat input welding of the steel plate, it is also beneficial to the improvement of the hydrogen sulfide stress corrosion resistance of the steel plate.

The above-mentioned manufacturing method of the strategic petroleum reserve tank steel plate based on oxide metallurgy comprises the following steps:

(1) Using the converter-LF-VD-continuous casting process, the continuous casting slab with the above composition is made; the thickness of the continuous casting slab is 260-300mm;

(2) After the continuous casting slabs are stacked for more than 24 hours, they are heated to 1100-1250°C in a heating furnace, and the casting slabs are in the furnace for no less than 4 hours, and then rough rolling and finish rolling are carried out; the rough rolling start temperature 1050～1100℃, the rough rolling pass deformation is 20～30%, the thickness of the intermediate billet to be cooled after the rough rolling is 2.0～3.5 times the thickness of the hot rolled plate; the finish rolling start temperature is 820～900℃, the pass The amount of deformation is 15-20%, and the final rolling temperature is 780-880°C; after finishing rolling, it is quickly transferred to an ultra-rapid cooling device, and is directly quenched and cooled to below 150°C at a speed of ≥50°C/s to obtain a hot-rolled sheet;

(3) Heat the hot-rolled plate to 600-700°C for 25-100 minutes for tempering heat treatment, and then air-cool to room temperature to make a steel plate for strategic oil storage tanks based on oxide metallurgy. The tempering heat treatment time is related to the thickness of the hot-rolled plate The relationship is determined by T=10+1.5min/mm×D; where T is the tempering heat treatment time, the unit is min; D is the thickness of the hot-rolled plate, the unit is mm.

In the converter-LF-VD-continuous casting process of the above step (1), when the molten steel reaches the LF furnace for refining, it is necessary to control the oxygen content to ≤150ppm by adding ferromanganese or ferrosilicon, and then add Ti element, and then Add one or more of Mg, RE, Ca or Zr elements, control the addition interval of each element to ≤10min, and then carry out LF furnace slagging, desulfurization and alloying; when the LF furnace refining is completed, control FeO+MnO in the slag The mass percentage of ≤ 1.5%.

The principle and advantages of the present invention are: using oxide metallurgy technology, the harmful inclusions in the steel are miniaturized and spheroidized to form composite inclusions with a controllable chemical structure and high melting point; the composite inclusions refer to: Inclusions formed by compounding Ti in Ti and one or more of oxides or sulfides such as Mg, Ca, B, Zr, Al, RE, etc.; due to this type of composite inclusions, it can be effectively pinned at high temperatures And to prevent the growth of austenite grains, during the cooling phase transformation process of the welding heat-affected zone (HAZ) structure, it can refine the original austenite grains and induce the formation of a large angle in the original austenite grains The grain-oriented fine acicular ferrite (AF), when the AF volume fraction induced by it reaches more than 80%, will greatly improve the low-temperature impact toughness of the steel plate in the high-heat input welding HAZ zone (such as -40 ° C Impact energy ≥ 80J).

The reasons for the chemical composition range limitation of the steel plate of the present invention are as follows:

C: It is an element required to ensure the strength of the steel plate; when the C content is lower than 0.03%, high strength cannot be guaranteed, and if the C content is higher than 0.10%, a large number of M-A island structures will be formed in the heat-affected zone of large heat input welding , welding crack sensitivity increases, reducing HAZ toughness;

Si: It is an element to ensure the strength of the steel plate and smelting deoxidation; if the Si content is too low, the deoxidation effect cannot be effectively exerted, and if it is too high, the welding heat-affected zone of the steel plate will become brittle, so the upper limit of Si is 0.3%;

Mn: It can ensure the strength of the steel plate and is beneficial to the toughness; if the Mn content is lower than 1.2%, the high strength and good toughness of the steel plate cannot be guaranteed; when the content is higher than 2.0%, the HAZ toughness will deteriorate during large heat input welding;

P: As an impurity element; if it exceeds 0.015%, the elongation and toughness of the steel plate will be significantly deteriorated, and it should be reduced as much as possible within the acceptable range of smelting costs;

S: It is an inevitable impurity element; an appropriate amount of S will form a high melting point sulfide, and at the same time, S in the steel will also attach around the composite oxide or nitride in the form of MnS, promoting acicular ferrite in the welding heat affected zone However, if the S content is too high, coarse inclusions will be generated, which will reduce the thickness direction performance of the steel plate. During the welding process, it will also peel off from the iron matrix and become the starting point of cracks, which will significantly increase the sensitivity of welding cracks. Therefore, the S content Should be less than 0.008%;

Al: It is an important deoxidizing element in the smelting process; the combination of Al and N can also increase the strength of the steel plate; an appropriate amount of Al is conducive to the formation of Ti oxides, and if it is greater than 0.03%, the toughness will deteriorate;

Ti: Appropriate Ti content and addition method can obtain a large number of small-sized Ti oxides and nitrides, improve the HAZ structure and refine the grains during high heat input welding, and improve toughness; if it exceeds 0.03%, the solid solution Ti increases, Coarse Ti oxides will be formed, which will significantly reduce the toughness;

Cu: Improve strength without reducing toughness, and increase corrosion resistance of steel plate; appropriate addition is beneficial to HAZ toughness, if Cu is lower than 0.01%, the strengthening effect cannot be obtained, and if it is higher than 1.0%, hot cracks will easily occur during welding, reducing HAZ toughness ;

Ni: It can ensure the strength and toughness of the steel plate, adding an appropriate amount can improve the toughness of the HAZ; if Ni is too low, a good strengthening and toughening effect cannot be obtained, and if it is added too much, the cost will increase; so the suitable range of Ni content is 0.01-1.0%;

Nb: In the process of controlled rolling, it can delay the occurrence of recrystallization, expand the range of austenite non-recrystallization zone, significantly improve the strain accumulation effect of deformed austenite, and is beneficial to the refinement of grain structure, but when the Nb content exceeds 0.03% It will deteriorate the low-temperature toughness of the welding heat-affected zone, so the limited Nb content should be less than 0.03%;

Cr and Mo: Both are elements that are beneficial to improving the strength of the steel plate. If the content exceeds 0.5%, the HAZ toughness will be significantly reduced, so the content of Cr and Mo is limited to less than 0.3%;

B: It can improve the hardenability of the thick plate and increase the strength of the steel plate, and in the process of large energy input welding, when the HAZ temperature is greater than 1300 ° C, TiN begins to dissolve, which increases the free N, and B diffuses quickly at high temperature, and it is easy to be welded in Austria. The grain boundary segregation of tenite is easy to combine with N to form BN during cooling, which can inhibit the formation and growth of grain boundary ferrite, which is beneficial to the improvement of HAZ toughness; therefore, the B content is required to be greater than 0.0001%, and if it exceeds 0.003%, the HAZ of the steel plate will be reduced. deterioration of toughness;

Ca, Mg, Zr, RE: all are strong deoxidizing elements and oxide or sulfide generating elements, and are also important additive elements for implementing the new oxide metallurgy process of the present invention. An appropriate amount of Ca can spheroidize the strip-shaped MnS-based inclusions, which helps to reduce the anisotropy of the steel plate and improve the performance in the Z direction; an appropriate amount of Ca, Mg, Zr, REM and appropriate addition methods will make the inclusions finer , increasing the nucleation particles of acicular ferrite is beneficial to HAZ toughness; the suitable ranges are Ca 0.0001～0.008%, Mg 0.0001～0.005%, Zr: 0.0001～0.02%, RE 0.0001～0.02%, if more than The upper limit will make the inclusions coarser, but deteriorate the HAZ toughness;

N: It is an essential element for the formation of TiN. If the N content is less than 20ppm, the precipitated TiN will be insufficient. If it is greater than 70ppm, the solid solution N will be excessive and the HAZ toughness will be reduced;

O: It can ensure the formation of oxides of Ti, Mg, Zr, RE and other elements. When the oxygen content is greater than 150ppm, the formed oxides are coarse and reduce the toughness of the HAZ.

The present invention replaces the existing reheating quenching+tempering (Q+T) or controlled rolling and controlled cooling+tempering (TMCP+T) technology with the online direct quenching+tempering (CRDQ+T) technology, so that the low carbon equivalent It is possible to produce high-strength, high-toughness and easy-to-weld oil storage tank steel plates under C _eq conditions; this is because a large number of crystal defects formed by the cumulative effect of deformation in the controlled rolling (CR) process have a genetic effect, making the deformed austenite rapidly cool The martensite lath formed in the phase transformation process has a small spacing and contains a large number of high-density dislocations. This lath martensite precipitates fine and dispersed alloy carbide particles during tempering, which improves the strength while improving the strength. , the effect of martensitic lath refinement and lath orientation diversification caused by deformation makes the fracture unit smaller and significantly improves the impact toughness of the steel plate; therefore, when producing steel plates of the same strength level, online direct quenching is used +The tempering process can not only save a lot of energy consumption and improve production efficiency, but also significantly reduce the carbon equivalent C _eq and alloy cost, which is conducive to the improvement of high heat input welding performance.

The steel plate of the present invention is also suitable for the manufacture of large-scale strategic oil storage tanks with a capacity of 100,000 cubic meters, 150,000 cubic meters and above; when the heat input is greater than 200KJ/cm, large heat input welding such as gas-electric vertical welding is performed, and post-weld welding The heat-affected zone (HAZ) at 2mm outside the fusion line has an impact energy of not less than 80J at -20°C; after adopting the steel plate of the present invention, it is expected that the double-sided double-pass X-type ( Also known as double V-type) welding method is changed to single-side single-pass V-type welding, which can reduce welding hours by nearly half, significantly increase the construction speed of oil storage tanks and greatly reduce the construction cost of strategic oil reserves, and has a good promotion Application prospect.

Description of drawings

Fig. 1 is the steel plate of strategic petroleum reserve tank based on oxide metallurgy in Example 1 of the present invention and the tempered martensite optical microstructure of steel plate obtained by comparative test; among the figure, a is the strategic petroleum reserve based on oxide metallurgy Tank steel plate, b is the steel plate obtained in the comparative test;

Fig. 2 is the steel plate of the strategic petroleum reserve tank based on oxide metallurgy in Example 1 of the present invention and the quenched SEM structure diagram of the steel plate obtained by the comparative test; among the figures, a is the steel plate of the strategic petroleum reserve tank based on oxide metallurgy, and b is The steel plate obtained by the comparative test;

Fig. 3 is the steel plate of strategic petroleum reserve tank based on oxide metallurgy in embodiment 2 of the present invention and the steel plate obtained by comparative test under the condition of heat input 200KJ/cm welding thermal simulation metallographic structure; among the figure a is obtained by comparative test steel plate, b is a steel plate for strategic petroleum reserve tanks based on oxide metallurgy;

Fig. 4 is the steel plate of the strategic oil reserve tank based on oxide metallurgy in the embodiment of the present invention 2 and the metallographic structure diagram of the steel plate obtained by the comparative test after the heat input is greater than 200KJ/cm gas-electric vertical welding; among the figure, a is based on Oxide metallurgy strategic oil storage tank steel plate, b is the steel plate obtained by the comparative test.

Detailed ways

The present invention will be described below by comparing different embodiments and comparative examples. These embodiments are only for the purpose of explanation. The present invention is not limited to these embodiments. All technologies formed by equivalent transformation or equivalent replacement schemes, all should fall within the scope of protection of the claims of the present invention.

In the embodiment of the present invention, the online direct quenching adopts the ultra-fast cooling device (FUC) developed by Northeastern University.

The RE used in the embodiment of the present invention is La or Ce.

Example 1

Converter-LF-VD-continuous casting process is used to make 260mm continuous casting slab; the chemical composition of continuous casting slab contains C0.07%, Si 0.16%, Mn 1.45%, P 0.010%, S 0.003%, Ni 0.16 in mass percentage %, Cu0.18%, B 0.002%, Cr0.10%, Mo 0.08%, Nb 0.02%, Al 0.01%, N 0.004%, O 0.003%, Ti 0.015%, Mg0.003%, RE 0.001%, Ca 0.003%, the balance is Fe; its carbon equivalent C _eq ＝C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15＝0.07+1.45/6+(0.1+0.08+0 )/5+(0.16+0.18)/15=0.37; when the molten steel reaches the LF furnace for refining, the oxide metallurgy process is used to control the oxygen content ≤ 150ppm through silicon and manganese deoxidation, and then Ti, Mg, RE and Ca are added, The above-mentioned ingredients are added at intervals of ≤10 minutes, and then LF furnace slagging, desulfurization and alloying are carried out. After the LF furnace refining is completed, the content of FeO+MnO in the slag is controlled to be ≤1.5% by mass percentage;

After the continuous casting slabs are stacked for 24 hours, they are transferred to the heating furnace and heated to 1150°C for 5 hours for rough rolling and finish rolling; The thickness of the intermediate slab when it is cooled after rolling is controlled by 2.0-3.5 times the thickness of the hot-rolled plate; the starting temperature of finish rolling is 860°C, the deformation of each pass is 15-20%, and the final rolling temperature is 830°C; Rapidly transferred to the ultra-fast cooling unit (FUC), directly quenched and cooled to below 150°C at a cooling rate of 50°C/s, and obtained hot-rolled sheets with a thickness of 10mm, 33mm, and 60mm by adjusting the thickness of the intermediate billet and the finishing pass. ;

Three sets of hot-rolled plates were heated to 650°C for tempering heat treatment. The tempering heating time T was 25, 59.5 and 100 minutes respectively. After tempering and heating, air-cooled to room temperature to make three sets of strategic oil storage tanks based on oxide metallurgy. The steel plates have yield strengths of 560, 530 and 510 MPa, tensile strengths of 630, 619 and 620 MPa, yield ratios of 0.89, 0.86 and 0.83, elongations of 20%, 21% and 22%, and -20 The ℃ impact energy is 248J, 283J and 272J respectively, and the conventional mechanical properties meet the requirements of the national standard GB19189-2011 "Quenched and Tempered High-Strength Steel Plates for Pressure Vessels".

comparative example

Converter-LF-VD-continuous casting process is used to make 260mm continuous casting slab; the chemical composition of continuous casting slab contains C0.10%, Si 0.22%, Mn 1.52%, P 0.010%, S 0.003%, Ni 0.20 in mass percentage %, Cu0.18%, B 0.002%, Cr0.20, Mo 0.10%, Nb 0.02%, V0.05%, Ca0.003%, Al 0.01%, N 0.004%, O 0.003%, the balance is Fe; Its carbon equivalent C _eq ＝C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15＝0.10+1.52/6+(0.2+0.1+0.05)/5+(0.20+0.18 )/15=0.45; when the molten steel reaches the LF furnace for refining, the oxide metallurgy process is not used, that is, deoxidation, slagging, desulfurization and alloying are carried out according to the traditional process, and there is no need to control the order of alloy addition, no need to control the oxygen content ≤ 150ppm, no need to Add special alloy elements such as Mg, RE, Zr;

After the continuous casting slabs are stacked for 24 hours, they are transferred to the heating furnace and heated to 1150°C for 5 hours for rough rolling and finish rolling; The thickness of the intermediate slab when it is cooled after rolling is controlled by 2.0-3.5 times the thickness of the hot-rolled plate; the starting temperature of finish rolling is 860°C, the deformation of each pass is 15-20%, and the final rolling temperature is 830°C; Transfer to the conventional controlled cooling device (ACC) to cool to 600-650°C at a cooling rate of 15-20°C/s, and obtain hot-rolled sheets with a thickness of 10mm, 33mm, and 60mm respectively by adjusting the thickness of the intermediate billet and the number of finishing passes;

Transfer the three groups of hot-rolled plates to the heat treatment workshop for off-line reheating at 940°C and then quenching + 650°C tempering. The quenching heating time T is calculated as T=10+1.4min/mm×D (plate thickness), and the tempering heating time T is calculated by T=10+1.5min/mm×D (plate thickness), and the steel plates are air-cooled to room temperature after tempering, and the yield strengths of the three groups of steel plates obtained in the comparative example are 580, 536 and 506 MPa, respectively, and the tensile strengths are 632, 506 MPa, respectively. 629 and 620MPa, the yield ratio is 0.92, 0.85 and 0.82, the elongation is 20%, 22% and 23%, and the impact energy at -20°C is 179J, 210J and 216J, except for the yield ratio of 10mm steel plate greater than 0.90 In addition, the rest of the mechanical properties meet the requirements of the national standard GB19189-2011 "Quenched and Tempered High-Strength Steel Plates for Pressure Vessels".

The optical microstructure of the online direct quenching+tempering steel plate of Example 1 with a thickness of 33mm and the comparative example offline quenching+tempering steel plate are shown in Figure 1, and the quenched SEM structure corresponding to the tempered martensite structure in Figure 1 is as follows As shown in Figure 2, it can be seen from Figures 1 and 2 that in Example 1, the effects of grain flattening, martensitic lath refinement and lath orientation diversification caused by the accumulation of strain in the non-recrystallized region before direct quenching are remarkable , so the steel plate of Example 1 using the direct quenching process has a better combination of strength and toughness, and there is no problem of high yield ratio of the thin-gauge steel plate; Special alloying elements such as Mg and RE can realize the miniaturization, spheroidization and composite control of inclusions in steel. These fine inclusions will directly or indirectly affect the solid-state phase transformation behavior of steel, so that steel can be used under low carbon equivalent conditions. In addition to being effectively strengthened, these highly micronized and spheroidized composite inclusions are also beneficial to the improvement of the hydrogen sulfide corrosion resistance of steel;

Embodiment 1 of the present invention and comparative example adopt NACETMO177-2005 and JB/T7901-1999 standard to detect the anti-hydrogen sulfide corrosion rate as shown in table 1;

Table 1

As can be seen from the data in Table 1, the hydrogen sulfide corrosion resistance rate of embodiment 1 is 0.3015mm/a on average, which is better than 0.3427mm/a of comparative example;

Example 2

Method is with embodiment 1, and difference is:

(1) The composition of the continuous casting billet contains C 0.08%, Si 0.20%, Mn 1.5%, P 0.010%, S0.003%, Ni 0.18%, B 0.002%, Cr 0.05%, Mo 0.1%, Nb by mass percentage 0.03%, Cu 0.08%, Al 0.02%, N 0.007%, O 0.006%, Ti 0.018%, Zr 0.010%, RE 0.001%, Ca 0.003%, the balance is Fe; C _eq ＝C+Mn/6+( Cr+Mo+V)/5+(Ni+Cu)/15=0.08+1.5/6+(0.05+0.1+0)/5+(0.18+0.08)/15=0.38;

(2) When refining in the LF furnace, add Ti, Zr, RE and Ca after controlling the oxygen content to ≤150ppm;

(3) The yield strengths of three groups of steel plates for strategic oil storage tanks based on oxide metallurgy are 572MPa, 546MPa and 498MPa, the tensile strengths are 636MPa, 630MPa and 626MPa, the yield ratios are 0.90, 0.87 and 0.81, and the elongation They are 21%, 23% and 23% respectively, and the impact energy at -20°C is 239J, 258J and 189J respectively;

Example 3

Method is with embodiment 1, and difference is:

(1) The thickness of the continuous casting slab is 300mm; the composition of the continuous casting slab contains C 0.09%, Si 0.3%, Mn 1.2%, P 0.011%, S 0.006%, Ni 0.20%, B 0.003%, Cr 0.3% by mass percentage %, Mo 0.08%, Nb 0.03%, Cu0.16%, N 0.007%, O 0.001%, Ti 0.022%, Zr 0.010%, Mg 0.003%, Ca 0.002%, Al0.025%; the balance is Fe; C _eq = C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15=0.09+1.2/6+(0.3+0.08+0)/5+(0.2+0.16)/15= 0.39;

(2) When refining in the LF furnace, after controlling the oxygen content to ≤150ppm, add Ti, Zr, Mg and Ca;

(3) The yield strengths of three groups of steel plates for strategic oil storage tanks based on oxide metallurgy are 568MPa, 556MPa and 499MPa, the tensile strengths are 636MPa, 632MPa and 626MPa, the yield ratios are 0.89, 0.88 and 0.80, and the elongations are respectively 21%, 23% and 24%, and the impact energy at -20°C is 219J, 238J and 259J, respectively.

The steel plates for strategic petroleum storage tanks based on oxide metallurgy obtained in Examples 1, 2, and 3 of the present invention and the 60mm steel plates obtained in comparative tests were subjected to welding thermal simulation tests at a peak temperature of 1400°C and heat input of 100 and 200KJ/cm respectively. The -20°C impact energy value is shown in Table 2;

Table 2

It can be seen from Table 2 that the simulated welding heat-affected zone -20°C impact energy values of the strategic oil reserve tank steel plate examples 1, 2 and 3 based on oxide metallurgy are all greater than 80J, while the simulated welding heat-affected zone -20°C of the comparative test steel plate Both the single value and the average value of the ℃ impact energy are less than 80J, which cannot meet the requirements of the national standard GB19189-2011.

Under the condition of simulated welding heat input of 200KJ/cm, the metallographic structure of the simulated welding heat of the comparative test steel plate and the steel plate of Example 1 is shown in Figure 3, as can be seen from the figure: the average grain size of prior austenite of the comparative test steel plate is 500 μm, Moreover, the proeutectoid ferrite at the austenite grain boundary is plate-shaped, and grows from the grain boundary to the grain to form side lath ferrite (or called Widmanstatten); while the strategic petroleum based on oxide metallurgy The average grain size of prior austenite in Example 1 of the storage tank steel plate is 180 μm, the proeutectoid ferrite at the austenite grain boundary is in the shape of polygonal agglomerates, and most of the intragranular structure is induced by fine inclusions It is composed of fine and dense acicular ferrite, so it has much higher low-temperature impact toughness in the simulated welding heat-affected zone than the comparative steel plate.

The 60mm steel plates obtained in Examples 1, 2, and 3 of the present invention and the 60mm steel plates obtained in the comparative examples were welded under the conditions of greater than 200KJ/cm of welding heat input after gas-electric vertical welding single-pass V-groove large heat input welding. The -20°C impact energy values of each part of the joint are shown in Table 3;

table 3

It can be seen from Table 3 that the impact energy values at -20°C at 2mm outside the fusion line of the welding heat affected zone of the steel plates of Examples 1, 2 and 3 based on oxide metallurgy are all greater than 80J, while the fusion line of the welding heat affected zone of the comparative test steel plate The impact energy value at -20°C at the outer 2mm is far lower than 80J, which does not meet the requirements of the national standard GB19189-2011. Since the 60mm steel plate is the most difficult to manufacture, and the 60mm steel plates of Examples 1, 2, and 3 have welding heat-affected zone-20°C impact energy values greater than 80J under the condition that the heat input is greater than 200KJ/cm, it is not difficult to infer that the whole of the present invention All steel plates with thickness specifications have the welding performance of large heat input that can withstand heat input greater than 200KJ/cm.

The metallographic structure of the welded heat-affected zone after gas-electric vertical welding of the steel plate of Example 2 and the comparative test steel plate based on oxide metallurgy under the condition of welding heat input greater than 200KJ/cm is shown in Figure 4, as can be seen from the figure, Example 2 The welding heat-affected zone structure of the steel plate is composed of a large number of interlocking fine acicular ferrite, while the welding heat-affected zone structure of the comparative test steel plate is composed of a large number of coarse side lath ferrite perpendicular to the original austenite grain boundary. Composition, the remarkable microstructure characteristics determine that the steel plate of the example based on oxide metallurgy has a large heat input welding performance with a heat input greater than 200KJ/cm, while the comparative test steel plate does not have the high heat input with a heat input greater than 200KJ/cm. Enter weld properties.

Claims (6)

1. a kind of strategic oil reserve tank steel plate based on Oxide Metallurgy, it is characterised in that ingredient contains C by mass percentage 0.03~0.10%, Si 0.10~0.30%, Mn 1.2~2.0%, P≤0.015%, S≤0.008%, Ti 0.005~ 0.03%, Ni 0.01~1.0%, B 0.0001~0.003%, Cr 0.05~0.5%, Mo 0.05~0.3%, Nb 0.01 ~0.03%, Cu 0.01~1.0%, Al 0.001~0.03%, N 0.002~0.007%, O 0.001~0.006%, also Containing one or more in Mg, Ca, Zr and RE, remaining is Fe and inevitable impurity；When containing Mg, Ca, Zr or RE, Content is respectively：Mg 0.0001~0.005%, Ca 0.0001~0.008%, Zr 0.0001~0.02%, RE 0.0001 ~0.02%；Its carbon equivalent C_eq≤ 0.40%；Wherein C_eq=C+Mn/6+ (Cr+Mo+V)/5+ (Ni+Cu)/15.

2. a kind of strategic oil reserve tank steel plate based on Oxide Metallurgy according to claim 1, it is characterised in that should 10~60mm of steel plate thickness, yield strength >=490MPa, 610~730MPa of tensile strength, elongation percentage >=17%, yield tensile ratio≤ 0.90, -20 DEG C of ballistic work >=80J.

3. a kind of strategic oil reserve tank steel plate based on Oxide Metallurgy according to claim 1, it is characterised in that should Contain titaniferous complex inclusion, 0.01~0.55 μm of the grain size of titaniferous complex inclusion, area density >=2.9 × 106 in steel plate A/mm²。

4. a kind of strategic oil reserve tank steel plate based on Oxide Metallurgy according to claim 3, it is characterised in that should The titaniferous complex inclusion quantity of steel plate is 4 times of traditional steel or more, while these field trashes have good affinity with MnS And MnS field trashes is made to be very easy to be gathered in its outer layer and be in spherical distribution, due to the high fine and ball of complex inclusion Shape, -20 DEG C of ballistic works are not under the conditions of heat input is more than 200KJ/cm after welding, at the outer 2mm of welding heat affected zone melt run Less than 80J, while being conducive to the raising of steel plate sulfurated hydrogen stress etching-resisting performance.

5. a kind of manufacturing method of the strategic oil reserve tank steel plate described in claim 1 based on Oxide Metallurgy, feature It is to include the following steps：

(1) converter-LF-VD- continuous casting process is used, the continuous casting billet of mentioned component is made；260~300mm of thickness of strand；

(2) after placing continuous casting billet stacking 24 hours or more, 1100~1250 DEG C are heated to by heating furnace, strand time inside furnace No less than 4 hours, then carry out roughing and finish rolling；Wherein 1050~1100 DEG C of roughing start rolling temperature, roughing pass deformation 20 ~30%, wait for that the cooling workpiece thickness of temperature is 2.0~3.5 times of hot rolling plate thickness after the completion of roughing；Finish rolling start rolling temperature 820 ~900 DEG C, pass deformation 15~20%, 780~880 DEG C of finishing temperature；It is transferred to ultra-rapid cooling rapidly after the completion of finish rolling Device is cooled to 150 DEG C hereinafter, obtaining hot rolled plate with the speed direct quenching of >=50 DEG C/s；

(3) hot rolled plate is heated to 600~700 DEG C of 25~100min of heat preservation and carries out tempering heat treatment, be then air-cooled to room temperature, make At the strategic oil reserve tank steel plate based on Oxide Metallurgy, tempering heat treatment time and the relationship of hot rolling plate thickness press T= 10+1.5min/mm × D is determined；T is back heating time, unit min in formula；D is hot rolling plate thickness, unit mm.

6. the manufacturing method of the strategic oil reserve tank steel plate according to claim 5 based on Oxide Metallurgy, feature It is in the converter-LF-VD- continuous casting process of step (1), it, need to be by the way that manganese be added when molten steel, which reaches LF stoves, to be refined The mode of iron or ferrosilicon controls oxygen content≤150ppm, then adds Ti elements, then adds one kind of Mg, RE, Ca or Zr element Or it is a variety of, control each element adds interval time≤10min, then carries out the slag making of LF stoves, desulfurization and alloying；When completion LF stoves After refining, mass percent≤1.5% of FeO+MnO in clinker is controlled.